JPH0812762B2 - Fault diagnosis device for detection switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a failure diagnosis device for various detection switches such as a proximity switch for confirming an object to be detected, a pressure switch, a limit switch, and the like. More specifically, the present invention relates to a failure diagnosis device capable of easily diagnosing a failure of the detection switch itself and a failure of a wiring system such as a power supply line or an output signal line of the detection switch.

(Prior Art) Before describing a conventional failure diagnosis apparatus, a conventional detection switch 12 will be described with reference to FIG. 9. A switch case 2 is provided with a sensor 3 for detecting an object to be detected.
Is connected to an operational amplifier 4 for amplifying a detection signal S1 output from the sensor 3 and comparing and discriminating between an open state and a closed state, and an output switching element 5 is connected to the operational amplifier 4. In addition, the case 2 has a terminal A of the DC power supply,
C and a signal output terminal B are provided. And the first
In the usage state shown in FIG. 0, the DC power supply 6 is connected between the terminals A and C, and the load resistor 7 of the switching element 5 is connected between the positive side terminal of the power supply 6 and the signal output terminal B. ing. An indicator lamp or a relay is used as the load resistor 7.

Then, when the detected object W approaches the sensor 3, the detection signal S1 output from the sensor 3 is input to the operational amplifier 4 for amplification discrimination, and the operation signal S2 (voltage) output from the operational amplifier 4 equal to or higher than a predetermined value. Is the output switching element 5
When the voltage is applied to the
A current i flows through the load resistor 7 through the load resistor 7 as shown in FIG. 11, and the display lamp and the relay are operated.
Further, when the detected part W is separated from the sensor 3, the detection signal S1 is not output from the sensor 3, and the operational amplifier 4
The operation signal S2 from is also stopped, the terminals B and C are opened, the current i becomes zero, and it is detected that the detected portion W does not exist.

(Problems to be solved by the invention) However, even when the detection switch 12 of the related art in the first half of the previous term is in the closed state as a result of the normal operation of the switching element 5, the short circuit between the terminals B and C is caused by the failure. , For example, when the external wiring l connected to the terminals B and C is in a short-circuited state, or when a component inside the detection switch 12 has a failure, for example, the switching element 5 is burned out, the terminals B and C are in a short-circuited state. In some cases, the current i flows in the same way as shown in FIG.
It is not possible to tell whether 12 is working properly or has been short-circuited due to said failure. Similarly, when the switching element 5 is in an open state as a result of normal operation, when there is a non-conduction state between the terminals B and C due to a failure, for example, when the wiring 1 is in a disconnection state, or the detection switch 12 Even when terminals B and C are open due to a failure of internal components such as burning of the switching element 5, the current i becomes zero and the detection switch 12 operates normally as shown in FIG. It is also impossible to distinguish whether it has operated due to a failure or an open state due to a failure. As a result, in order to confirm whether the detection switch 12 is normal or abnormal, the detection switch 12 is operated under both operating conditions, that is, the detection switch 12 is in the closed state and the open state.
Not only is there a problem of having to perform each of the troublesome and complicated steps of checking the output status of each, but it is not possible to check whether or not the detection switch is operating normally in a mechanical device that uses the detection switch. The problem was that it was difficult.

Configuration of the Invention (Means for Solving the Problems) In order to solve the above problems, the first aspect of the invention periodically detects a detection signal output from the sensor unit of the detection switch when the detection signal is in the closed state. An open signal is given, and when the detection signal output from the sensor section is in an open state, a failure diagnosis signal giving means for giving a close signal to the detection signal is provided, and further output from the sensor section of the detection switch. In the normal state of the detection switch by the open / closed signal detection circuit that determines the presence or absence of the open signal in the closed state and the open / closed signal detection circuit in the open state, and the output signal from the open / closed signal detection circuit, A discrimination operation circuit that outputs a normal signal and outputs an abnormal signal in an abnormal state is provided separately from the detection switch, and on the control target side where the output signal of the detection switch is output. It has taken a means of connecting to the detection switch.

In addition to the structure of the first aspect of the invention, the second aspect of the invention employs means for providing a fault diagnosis signal cancel circuit for removing the fault diagnosis signal from the output signal.

(Operation) The present invention operates as follows by adopting the above means.

According to a first aspect of the present invention, an open / close signal detection circuit determines whether or not an open signal or a closed signal is present in the output signal from the detection switch. When the open signal or the closed signal is present, the determination operation circuit detects the detection switch. When the normal signal is output and the open signal or the closed signal does not exist, an abnormal signal due to short circuit or disconnection of the wiring connected from the detection switch to the outside is output.

Further, in the second invention, in addition to the operation of the first invention, since the open signal or the closed signal in the output signal from the detection switch is removed, the operation of the control device connected to the failure diagnosis device is surely performed. .

(Embodiment) Before describing the failure diagnosis apparatus of the present invention, an embodiment of a detection switch proposed by the inventor of the present application will be described with reference to FIGS.
It will be described with reference to the drawings. In the detection switch 1 of this embodiment, members having the same functions as those of the conventional detection switch 12 described above are designated by the same reference numerals, and the description of the configuration will be omitted.

The sensor 3 is connected in parallel with a forced opening / closing operation control device 9 composed of an oscillator. Further, a forced open switch is provided between the output terminal E of the sensor 3 and the positive power source terminal A.
10 is connected so that the opening operation is performed by the operation signal S3 from the forced opening / closing operation control device 9. Similarly, the output terminal E of the sensor 3 and the negative power supply terminal C
A forcible closing switch 11 is connected between the above and the forcible closing switch 11 so that the closing operation is performed by an operation signal S4 from the forcible opening / closing operation control device 9.

When the detection signal S1 of the detection switch 1 and the operation signal S2 are in the closed state in the use state (see the chain line in FIG. 6), that is, as shown in FIG.
When the current flowing between C (hereinafter referred to as the output signal S of the detection switch 1) is flowing by a predetermined value i, the forced opening switch 10 is opened by the operation signal S3 from the forced opening / closing operation control device 9 and forced. The open signal S5 as a failure diagnosis signal for a short time (for example, 1 msec or less) periodically and periodically to the detection signal S1, thereby giving the open signal S5 to the operation signal S2 and the output signal S thereafter. I am trying to do it.

On the contrary, when the output signal S is in the open state, that is, when the current is zero as shown in FIG. 8, the operation signal S4 from the forcible opening / closing operation control device 9 operates the forcible closing switch 11 to forcibly And periodically for a short time (for example, 1 msec)
An open signal S6 as the following failure diagnosis signal is given to the detection signal S1, and a closing signal S6 is given to the subsequent operation signal S2 and output signal S. As described above, the forced opening / closing operation is performed by a relay having a responsiveness of several msec if it is operated for a short time within a range that can be discriminated from the normal output signal S of the switch.
There is no effect even if it is used for a control device (not shown) such as a programmable controller.

Further, the operation of applying the fault diagnosis signals S5, S6 can be performed arbitrarily or independently periodically by applying a control signal to the forced opening / closing operation control device 9 from the outside.

In this embodiment, the forced opening / closing control device 9, the forced open switch 10 and the forced close switch 11 constitute a failure diagnosis signal giving means. Further, the detection signal from the sensor 3 is generated by the operational amplifier 4 and the output switching element 5.
It constitutes an opening / closing signal output means that is closed or opened by S1.

Next, a first embodiment of the failure diagnosis apparatus of the present invention for diagnosing the failure of the detection switch 1 will be described with reference to FIG.

The case 14 of the failure diagnosis device 13 has output signals S to S output from the plurality of detection switches 1 to 1 described above, respectively.
Is provided with a plurality of input terminals 15a to 15n.

On the other hand, at the input terminals 15a to 15n, as an open / closed signal detection circuit for detecting whether or not the open signal S5 or the closed signal S6 for fault diagnosis is present in the output signals S to S, respectively. Edge detection circuits 16a to 16n are connected. or,
The edge detection circuits 16a to 16n output a low voltage when an edge is detected in the closed state or the open state, and when the edge is not detected, a retriggerable one-shot as a determination operation circuit for outputting a high voltage. Multivibrators 17a to 17n are connected in series. Further, light emitting diodes 18a to 18n are connected to the retriggerable one-shot multivibrators 17a to 17n, and the detection switch 1
When ~ 1 is normal, that is, when an edge is detected, it is conducted and turned on, and when no edge is detected, it is turned off.

On the other hand, each one-shot multivibrator 17a-1
A gate circuit 20 for outputting to 7n a signal capable of determining the presence or absence of a failure for each failure diagnosis device 13, that is, a high voltage when an edge is detected and a low voltage when an edge is not detected. Is connected and its output terminal 21 is the case
It is provided in 14.

Then, the failure diagnosis device 13 detects the detection switches 1 to
The presence or absence of the open signal S5 or the closed signal S6 included in the output signal S of 1 is determined and displayed. That is, when any one of the signals S5 and S6 is present in the output signal S, the edge detection circuits 16a to 16n and the worstion multivibrator 17a to 1n are provided.
The detection switch 1 is diagnosed as normal by 7n. On the contrary, if the signals S5 and S6 do not exist within a certain period of time, it is diagnosed that the detection switch 1 is abnormal, or the wiring 1 from the detection switch 1 is broken or short-circuited, and the diagnosis result is Light emitting diodes 18a-18n
And is input to the external control device from the output terminals 19a to 19n.

Further, the input terminals 15a to 15n have the output signals S to
A constituent element of the digital or analog second invention for removing the open signal S5 or the closed signal S6 in S, that is, a filter circuit as a failure diagnosis signal cancel circuit.
22a to 22n are connected, and the output signal S passing through the filter circuits 22a to 22n is output from the output terminals 23a to 23n of the case 14 to the external control device.

Now, in the embodiment of the first invention, the edge detection circuits 16a to 16n for discriminating whether or not the open signal S5 or the closed signal S6 is present in the output signal S outputted from the detection switch and the edge detection circuits 16a to 16n are outputted. If there is an open signal or a closed signal due to this signal, the normal signal of the detection switch 1 is output by the multivibrator 17a to 17n, and if it does not exist, the detection switch 1 is abnormal or the detection switch 1 and the control device are connected. Since the abnormality signal indicating the abnormality due to the disconnection or short circuit of the external wiring l to be connected is output, the detection switch 1
It is possible to easily and easily discriminate a failure of itself and a failure based on an external factor such as the wiring 1 during the operation of the detection switch 1.

Next, a second embodiment of the present invention will be described with reference to FIGS.

A fault diagnostic pulse generator 25 as a fault diagnostic signal providing means and a pulse coincidence detection circuit 26 are housed in a case 27, and a fault diagnostic pulse signal S7 is output from an output terminal 28 to a detection switch 29 to detect the detection switch 29. The output signal S given the open signal S5 or the close signal S6 by the forced open switch 10 or the forced close switch 11 is input to the input terminal 30.
Further, a terminal 31 for inputting the failure diagnosis command signal S8 and a terminal 32 for outputting the failure diagnosis signal S9 are provided.

The pulse coincidence detection circuit 26 is constructed as shown in FIG.

Reference numeral 35 in the drawing indicates a change in the signal generated by the output signal S of the detection switch 1 during the output of the failure diagnosis pulse signal S7 (current i), that is, from the open state to the closed state and from the closed state to the open state.
It is a conversion circuit that constantly converts from a low level to a high level, and is composed of a D type flip-flop circuit 36, an Ex OR circuit 37, and an AND circuit 38.

Further, reference numeral 39 indicates a high level signal Hi only when there is a rising pulse Pu from the conversion circuit 35, that is, a rising pulse Pu from a low level to a high level during the output of the failure diagnosis pulse signal S7 (high level). Which is a high-level pulse determination circuit for outputting a D-type flip-flop circuit 36 '.
And an OR circuit 40.

Further, reference numeral 41 is an output holding circuit that holds the output result of the high-level pulse discrimination circuit 39 at the time when the failure diagnosis pulse signal S7 ends until the next failure diagnosis. And a circuit 36 ″. Then, when the detection switch 1 is normal, it outputs a high level current, and when abnormal due to a disconnection or short circuit of the wiring l from the detection switch 1 to the outside, a low level current ( It outputs zero).

In the second embodiment, the original detection switch 29 and the failure diagnosis signal providing means are separately provided, but in this case as well, the failure of the detection switch 29 itself and the failure due to an external factor can be discriminated.

Next, a third embodiment of the present invention will be described with reference to FIG.

In addition to the embodiment shown in FIGS. 2 and 3 described above, a failure diagnosis pulse cancel circuit 33 is built in, and an output signal S without the closed signal S6 or the open signal S5 can be taken out from there by an output terminal 34. To do.

In the case of this embodiment, the forced opening / closing operation does not appear in the output signal S of the failure diagnosis device, and the output of the detection switch 29 is not delayed.

 A fourth embodiment of the present invention will be described with reference to FIG.

In this embodiment, an input unit 42 with a failure diagnosis function for inputting the output signal S output from the detection switches 1 to 1 and inputting it to a control device (not shown) is used.
Explaining the input unit 42, the case 43 has an input terminal 44 for inputting the output signals S of the detection switches 1 to 1.
a to 44n are provided, and an insulating circuit 45 for extracting only a signal is connected to each of the input terminals. A filter circuit 46 and an edge detection circuit 47 are connected in parallel to the insulating circuit 45, and a display circuit for displaying an open state or a closed state.
48 are connected.

A data selection circuit 49 is connected to the filter circuit 46, an address decoder 50 is connected to the selection circuit 49, and is connected to a motherboard connector 51.
The signal S from each of the detection switches 1 to 1 is input to the control device (not shown) from 51 without the open signal S5 or the closed signal S6.

A retriggerable one-shot multivibrator 52 is connected to the edge detection circuit 47, a data selection circuit 53 is connected to the multivibrator 52, and is connected to a mother board connector 51 via a data bus buffer 54. Further, a gate circuit 55 is connected to the retriggerable one-shot multivibrator 52, and the input unit
A signal for determining whether the detection switch 1 is normal or abnormal for each 42 is output to the connector 51.

In the fourth embodiment, the input unit 42 with a failure diagnosis function is used.
The wiring from the control device to the control device can be omitted.

The present invention can also be embodied as follows.

In the above embodiment, the electric detection switch is embodied, but it is embodied as a magnetic sensor or an optical sensor (not shown),
The failure diagnosis device may detect an open signal or a closed signal in the magnetic signal or the optical signal output from the device.

As described in detail above, the first aspect of the present invention is capable of reliably and quickly determining not only a failure of the detection switch itself but also an abnormality in the wiring from the detection switch to another control device while the detection switch is in use. There is an effect that can be.

Further, in addition to the effect of the first invention, the second invention can remove the open signal or the closed signal from the output signal, so that there is an effect that the operation of another control device can be surely performed.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment embodying the present invention,
FIG. 2 is a block circuit diagram showing a second embodiment of the present invention, FIG. 3 is a circuit diagram showing an essential part of the second embodiment, and FIG. 4 is a block circuit diagram showing a third embodiment of the present invention. FIG. 5 is a block circuit diagram showing a fourth embodiment of the present invention, FIG. 6 is a circuit diagram showing an embodiment of the detection switch, and FIGS. 7 and 8 are graphs showing the operating state of the detection switch. FIG. 9 is a circuit diagram of a conventional detection switch, FIG. 10 is a circuit diagram showing a usage state of the conventional detection switch, and FIG. 11 is a graph showing an operation state of the detection switch. Detection switch 1, switch case 2, sensor 3, operational amplifier 4, output switching element 5, DC power supply 6, load resistor 7, forced opening / closing operation control device 9 constituting a failure diagnosis signal providing means, forced open switch 10, forced Close switch 11,
Edge detection circuits 16a to 16n as open / closed signal detection circuits,
Retriggerable one-shot multivibrator 17a to 17n as a determination operation circuit, failure diagnosis pulse generator 25 as a failure diagnosis signal applying means, detection switch 29, failure diagnosis pulse cancel circuit 33 as a failure diagnosis signal cancel circuit, conversion Circuit 35, flip-flop circuit 36,3
6 ′, 36 ″, detection signal S1, power supply terminals A, C, signal output terminal B, operation signals S2, S3, S4, current i as output signal S, open signal S5 as failure diagnosis signal, failure diagnosis Closed signal S6 as a signal for fault diagnosis pulse signal S7.

Claims (2)

[Claims] 1. When the detection signal output from the sensor section of the detection switch is in the closed state, an open signal is periodically given to the detection signal, and the detection signal output from the sensor section is in the open state. In the above, there is provided a failure diagnosis signal giving means for giving a closing signal to the detection signal, and further, the detection signal output from the sensor part of the detection switch has an open signal in the closed state, and has a closed signal in the open state. An open / closed signal detection circuit that determines whether the detection switch is in a normal state and a determination operation circuit that outputs an abnormal signal in an abnormal state based on the output signal from the open / closed signal detection circuit. A detection switch failure diagnosis apparatus, which is provided separately from the detection switch and is connected to the detection switch on the side of a controlled object to which an output signal of the detection switch is output. 2. When the detection signal output from the sensor section of the detection switch is in the closed state, an open signal is periodically given to the detection signal, and the detection signal output from the sensor section is in the open state. In the above, there is provided a failure diagnosis signal giving means for giving a closing signal to the detection signal, and further, the detection signal output from the sensor part of the detection switch has an open signal in the closed state, and has a closed signal in the open state. An open / closed signal detection circuit that determines whether the detection switch is in a normal state by the output signal from the open / closed signal detection circuit, and a determination operation circuit that outputs an abnormal signal in an abnormal state; A failure diagnosis signal cancel circuit for removing the failure diagnosis signal from the output signal, and a control circuit for outputting the output signal of the detection switch, the circuit being provided separately from the detection switch. Detection switch failure diagnosis apparatus being characterized in that connected to the detection switch at the target side.